How patio heaters work
Patio heaters that are fuelled by LPG produce radiant heat. LPG (liquid petroleum gas) cylinders connect to the patio heater using an approved gas regulator. The regulator is specifically designed to control the flow of gas from the LPG cylinder to the patio heater burner. Regulators in the UK are available to fit propane cylinders operating at 37mbar and butane cylinders operating at 28mbar. The regulator maintains the correct flow entering the patio heater burner chamber. The regulator will be connected from the cylinder via a LPG high pressure hose which in turn is connected to the burner.
Older patio heater burners operate by lighting a pilot light (fired via the piezo ignitor) before firing the main gas chamber. Newer burner use continuous pilot system. Both system require the thermocouple to reach the required temperature before firing the gas chamber.
The patio heater gas control valve will be connected to a flame failure device and if fitted a tilt switch. The tilt switch is designed to shut the gas supply off should the patio heater tilt by more than 30 degrees.
Patio heater burners are measured in BTU/h - British Thermal Unit. Radiant heat produced by the burner is reflected towards the ground via the reflector.
The height and size of the patio heater reflector is designed to force radiant heat downwards heating a large area under the reflector, typically around 6 metres. To work efficiently the patio heater height will be a minimum 2 metres with a reflector size of 80cm minimum. Radiant heat is a form of energy that heats objects close to the patio heater directly through a process called conversion without having to heat the air between. Radiant heat is also called infrared energy or IR. The electromagnetic spectrum is divided into three segments by wavelength, measured in microns or micrometers (a micron = 1/1,000,000 of a meter): 0.076 to 1.5 microns = near or close; 1.5 to 5.6 = middle or intermediate; 5.6 to 1000 = far or long wave infrared. Patio heaters produce the same natural heating effect of the sun.
Most of the energy produced by the sun is within the infrared segment of the spectrum. The atmosphere allows infrared rays within 7 to 14 micron ranges to safely reach the surface of the earth. When the earth is warmed it radiates infrared rays within 7 to 14 micron bands.
Gas patio heaters feel just like the sun, warming people and objects, while not wasting valuable energy trying to heat air. The infrared heat will provide warmth much like the sun’s gentle waves but without the harmful UV rays.
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